For some reasons, you removed an App from the Applications folder, but the App Icon still appears in the Launchpad. When you click on that icon, it only shows the error message. That icon becomes useless.

You want to remove that icon from the Launchpad, but you can’t right click the icon to remove it nor drag and drop it into the trash.

Here is a trick to remove it.

1. Open Terminal, run the following command

sudo find /var/folders -name

It will show you where the Launchpad folder locates.
In My Mac, it shows:


2. Open that folder

open /var/folders/xw/88q1ph5s1pz4737f6cy1gn6h0000gn/0/

3. Open the db folder inside
In the db folder, there are 3 files: db, db-shm, db-wal.

4. Open the db file
This db file is a SQLite DB file. You can open it easily using DB Browser for SQLite, or using sqlite3 command line (up to you).

5. Check apps table
Here it is! There is a table named apps containing all the information of app icon in Launchpad.
If you are using DB Browser for SQLite, you can see its data easily. Just click Browse Data tab, choose apps from Table.
Choose the line of the Icon you want to remove and click Delete Record.
Remember to save your changes before close.

6. Log out and log in back
Check if it works!